The present invention relates to a fuel blending system, and more particularly to a moveable or mobile fuel emulsion blending system for blending an aqueous fuel emulsion from a source of hydrocarbon fuel, a source of water, and a source of fuel emulsion additives.
Recent fuel developments have resulted in a number of water blend fuel emulsions or aqueous fuel emulsions comprised essentially of a carbon based fuel, water, and various additives such as lubricants, emulsifiers, surfactants, corrosion inhibitors, cetane improvers, and the like. These fuel emulsions may play a key role in finding a cost-effective way for internal combustion engines including, but not limited to, compression ignition engines (i.e. diesel engines) to achieve the reduction in emissions below the mandated levels without significant modifications to the engines, fuel systems, or existing fuel delivery infrastructure.
Advantageously, water blend fuel emulsions tend to reduce or inhibit the formation of nitrogen oxides (NOx) and particulates (i.e. combination of soot and hydrocarbons) by altering the way the fuel is burned in the engine. Specifically, the fuel emulsions are burned at somewhat lower temperatures than a conventional diesel fuel due to the presence of water. This, coupled with the realization that at higher peak combustion temperatures, more NOx are typically produced in the engine exhaust, one can readily understand the advantage of using water blend fuel emulsions.
A major concern of such aqueous fuel emulsions or water blend fuels, however, is the stability of the fuel. As is well known in the art, the constituent parts of such fuel emulsions have a tendency to separate over time. Blending of the fuel emulsions in a manner to achieve long-term stability is essential if such fuels are to be commercially successful. The problems associated with fuel emulsion separation are very severe inasmuch as most engine operating characteristics are adjusted for a prescribed fuel composition. Where the fuel emulsion composition has changed due to ingredient separation, the engine performance is markedly diminished.
Several related art references have disclosed various devices or techniques for producing or blending a fuel emulsion for internal combustion engines. For example, U.S. Pat. No. 5,535,708 (Valentine) discloses a process for forming an emulsion of an aqueous urea solution in diesel fuel and combusting the same for the purposes of reducing NOx emissions from diesel engines. See also U.S. Pat. No. 4,938,606 (Kunz) discloses an apparatus for producing an emulsion for internal combustion engines that employs an oil line, a water line, a dosing apparatus and various mixing and storage chambers. Another related art process and system for blending a fuel emulsion is disclosed in U.S. Pat. No. 5,298,230 (Argabright) which discloses a specialized process for blending a fuel emulsification system useful for the reduction of NOx in a gas turbine.
The present invention addresses the aforementioned problems associated with separation of water blend and aqueous fuel emulsions by providing a blending system and method that enhances the long term stability of such emulsions.
The present invention is a transportable fuel emulsion blending system for blending a fuel emulsion from a source of hydrocarbon fuel, a source of water, and a source of fuel emulsion additives. Advantageously, the blending system enhances the long term stability of such fuel emulsions over that of conventional blending systems.
The present invention may be characterized as a transportable fuel emulsion blending system for blending a fuel emulsion from a source of water, a source of hydrocarbon fuel, and a source of fuel emulsion additives. The fuel emulsion blending system includes a transportable platform, such as a vehicle or moveable skid; a hydrocarbon fuel circuit and a fuel emulsion additive circuit both disposed on the platform; and a first blending station disposed on the platform and adapted to mix the hydrocarbon fuel and the fuel emulsion additives. The transportable fuel emulsion blending system also includes a second blending station disposed on the platform and adapted to mix the hydrocarbon fuel-additive mixture together with the water, and an emulsification station also disposed on the platform and adapted to emulsify said hydrocarbon fuel, fuel emulsion additive, and water mixture to yield a stable fuel emulsion.
An important aspect of the disclosed transportable fuel emulsion blending system is the ability for the blending system to be readily transportable from a first fueling location to an alternate fueling location. In addition, the disclosed fuel emulsion system is particularly suitable for blending fuel continuous fuel emulsions, although water continuous fuel emulsions can likewise be blended. Where water continuous emulsions are desired, the water-soluble fuel emulsion additives could be first combined with the water and subsequently mixed with the hydrocarbon. Moreover, the presently disclosed fuel emulsion blending system can also be easily adapted to blend fuel emulsions containing additional freeze depressants, such as methanol in addition to the standard fuel emulsion additive package.
Another important aspect of the presently disclosed embodiments of the fuel emulsion blending system is that it is operatively associated with a blending system controller. The blending system controller is adapted to govern the flow of the hydrocarbon fuel, water and fuel emulsion additives thereby controlling the mixing ratio in accordance with prescribed blending ratios.